Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “BAG MODEL”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Lattice QCD Study for Confinement in Hadrons

We study three subjects on quark confinement in hadrons in SU(3)c lattice QCD. From the accurate lattice calculation for more than 300 different patterns of three-quark (3Q) systems, we find that the static 3Q potential is well described by Y-Ansatz, i.e., the Coulomb plus Y-type linear potential. We also study the multi-quark (4Q, 5Q) potentials in lattice QCD, and find that they are well described by the one-gluon-exchange (OGE) Coulomb plus string-theoretical linear potential, which supports the infrared string picture even for the multi-quarks. The second subject is a lattice-QCD determination of the relevant gluonic momentum component for confinement. The string tension (confining force) is found to be almost unchanged even after cutting off the high-momentum gluon component above 1.5GeV in the Landau gauge. In fact, quark confinement originates from the low-momentum gluon below about 1.5GeV. Finally, we consider a possible gauge of QCD for the quark potential model, by investigating 'instantaneous inter-quark potential' in generalized Landau gauge, which describes a continuous change from the Landau gauge to the Coulomb gauge.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

On spectroscopy for a whole Abelian model

Postulated on the whole meaning a whole abelian gauge symmetry is being introduced. Various physical areas as complexity, statistical mechanics, quantum mechanics are partially supporting this approach where the whole is at origin. However, the reductionist crisis given by quark confinement definitely sustains this insight. It says that fundamental parts can not be seen isolatedely. Consequently, there is an experimental situation where the parts should be substituted by something more. This makes us to look for writing the wholeness principle under gauge theory. For this, one reinterprets the gauge parameter where instead of compensating fields it is organizing a systemic gauge symmetry. Now, it introduces a fields set {l_brace}A{sub {mu}I}{r_brace} rotating under a common gauge symmetry. Thus, given a fields collection {l_brace}A{sub {mu}I}{r_brace} as origin, the effort at this work is to investigate on its spectroscopy. Analyze for the abelian case the correspondent involved quanta. Understand that for a whole model diversity replaces elementarity. Derive the associated quantum numbers as spin, mass, charge, discrete symmetries in terms of such systemic symmetry. Observe how the particles diversity is manifested in terms of wholeness.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Two-Color PNJL Model and Equation of State of Hadrons at Finite Temperature and Density

We derive hadronic chiral Lagrangian from PNJL model by using bosonization method. Bosonization is based on path integral, quark fields are integrated out by introducing the auxiliary fields. By its nature, this method is difficult to apply the problem of three bodies, but it is stand up for two-bodies. Hence this method usually have been applied meson theory. We attempt bosonization to be enlarged including baryon in two-color scheme. The obtained model which has chiral symmetry and quark confinement property apply to finite temperature and density, and find out the thermodynamical property. We make a comparison with lattice QCD sumilation in two-color at finite density.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Entanglement between the Deconfinement and the Chiral Symmetry Restoration

We extend the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model by introducing an effective four-quark vertex depending on the Polyakov loop. The effective vertex generates entanglement interactions between the Polyakov loop and the chiral condensate. The new model is consistent with lattice QCD data at imaginary quark-number chemical potential and real and imaginary isospin chemical potentials. We investigate the influence of the entanglement interactions on the location of the critical endpoint at real quark-number chemical potential.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

On whole Abelian model dynamics

Physics challenge is to determine the objects dynamics. However, there are two ways for deciphering the part. The first one is to search for the ultimate constituents; the second one is to understand its behaviour in whole terms. Therefore, the parts can be defined either from elementary constituents or as whole functions. Historically, science has been moving through the first aspect, however, quarks confinement and complexity are interrupting this usual approach. These relevant facts are supporting for a systemic vision be introduced. Our effort here is to study on the whole meaning through gauge theory. Consider a systemic dynamics oriented through the U(1) - systemic gauge parameter which function is to collect a fields set {l_brace}A{sub {mu}I}{r_brace}. Derive the corresponding whole gauge invariant Lagrangian, equations of motion, Bianchi identities, Noether relationships, charges and Ward-Takahashi equations. Whole Lorentz force and BRST symmetry are also studied. These expressions bring new interpretations further than the usual abelian model. They are generating a systemic system governed by 2N+ 10 classical equations plus Ward-Takahashi identities. A whole dynamics based on the notions of directive and circumstance is producing a set determinism where the parts dynamics are inserted in the whole evolution. A dynamics based on state, collective and individual equations with a systemic interdependence.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Elastic electron-deuteron scattering in the light-front Hamiltonian dynamics

Within the Light-Front Hamiltonian Dynamics, we are extending our investigation of the deuteron electromagnetic properties by adding new, dynamical two-body terms to the one-body current operator, introduced in previous works. These two-body contributions are generated in a four-dimensional Yukawa model (two fermions interacting through a pion) from an analysis of the Light-Front-projected current that acts on the three-dimensional valence component and fulfills the Ward-Takahashi identity. Preliminary results for the magnetic moment and the non valence probability are shown.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Study of the deconfinement phase transition in a finite volume with massive particles: Hydrodynamics of the system near the transition

We study the finite size and finite mass effects for the thermal deconfinement phase transition in Quantum Chromodynamics (QCD), using a simple model of coexistence of hadronic (H) gas and quark-gluon plasma (QGP) phases in a finite volume. We consider the equations of state of the two phases with the QGP containing two massless u and d quarks and massive s quarks, and a hadronic gas of massive pions, and we probe the system near the transition. For this, we examine the behavior of the most important hydrodynamical quantities describing the system, at a vanishing chemical potential ({mu}= 0), with temperature and energy density.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

QCD Phase Diagram at Finite Baryon and Isospin Chemical Potentials

The phase structure of two-flavor QCD is explored for finite temperature T and finite baryon- and isospin-chemical potentials, {mu}{sub B} and {mu}{sub I}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data in the {mu}{sub I}-T plane at {mu}{sub B} = 0. In the {mu}{sub I}-{mu}{sub B}-T space, the critical endpoint of the chiral phase transition in the {mu}{sub B}-T plane at {mu}{sub I} = 0 moves to the tricritical point of the pion-superfluidity phase transition in the {mu}{sub I}-T plane at {mu}{sub B} = 0 as {mu}{sub I} increases.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Sigma meson and lowest possible glueball candidate in an extended linear {sigma} model

We formulate an extended linear {sigma} model of a quarkonia nonet and a tetraquark nonet as well as a complex iso-singlet (glueball) field to study the low-lying scalar meson. Chiral symmetry and U{sub A}(1) symmetry and their breaking play important role to shape the scalar meson spectrum in our work. Based on our study we will comment on what may be the mass of the lowest possible scalar and pseudoscalar glueball states. We will also discuss on what may be the nature of the sigma or f{sub 0}(600) meson.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Highlights in light-baryon spectroscopy and searches for gluonic excitations

The spectrum of excited hadrons - mesons and baryons - serves as an excellent probe of quantum chromodynamics (QCD), the fundamental theory of the strong interaction. The strong coupling however makes QCD challenging. It confines quarks and breaks chiral symmetry, thus providing us with the world of light hadrons. Highly-excited hadronic states are sensitive to the details of quark confinement, which is only poorly understood within QCD. This is the regime of non-perturbative QCD and it is one of the key issues in hadronic physics to identify the corresponding internal degrees of freedom and how they relate to strong coupling QCD. The quark model suggests mesons are made of a constituent quark and an antiquark and baryons consist of three such quarks. QCD predicts other forms of matter. What is the role of glue? Resonances with large gluonic components are predicted as bound states by QCD. The lightest hybrid mesons with exotic quantum numbers are estimated to have masses in the range from 1 to 2 GeV/c{sup 2} and are well in reach of current experimental programs. At Jefferson Laboratory (JLab) and other facilities worldwide, the high-energy electron and photon beams present a remarkably clean probe of hadronic matter, providing an excellent microscope for examining atomic nuclei and the strong nuclear force.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Clustering effects for explaining an anomalous JLab result on the {sup 9}Be structure function

An anomalous nuclear modification was reported by JLab measurements on the beryllium-9 structure function F{sub 2}. It is unexpected in the sense that a nuclear modification slope is too large to be expected from its average nuclear density. We investigated whether it is explained by a nuclear clustering configuration in {sup 9}Be with two {alpha} nuclei and surrounding neutron clouds. Such clustering aspects are studied by using antisymmetrized molecular dynamics (AMD) and also by a simple shell model for comparison. We consider that nuclear structure functions F{sub 2}{sup A} consist of a mean conventional part and a remaining one depending on the maximum local density. The first mean part does not show a significant cluster effect on F{sub 2}. However, we propose that the remaining one could explain the anomalous JLab slope, and it is associated with high densities created by the cluster formation in {sup 9}Be. The JLab measurement is possibly the first signature of clustering effects in high-energy nuclear reactions. A responsible physics could be an internal nucleon modification, which is caused by the high densities due to the cluster configuration.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Diffractive Dissociation into {pi}{sup -{pi}-{pi}+} Final States at COMPASS

QCD predicts gluonic excitations like hybrids to contribute to the meson spectrum in addition to qq-bar pair configurations. The most promising way to identify such states is the search for J{sup PC} quantum number combinations which are forbidden in the constituent quark model. The fixed target COMPASS experiment at CERN offers the opportunity to search for such states in the light quark sector with an unprecedented statistics.Diffractive reactions of 190 GeV/c pions on a lead target were studied by COMPASS during a pilot run in 2004. A Partial Wave Analysis (PWA) of the {pi}{sup -{pi}-{pi}+} final state with 42 waves including acceptance corrections through a phase-space Monte Carlo simulation of the spectrometer was performed. The exotic {pi}{sup 1}(1600) meson with quantum numbers J{sup PC} = 1{sup -+} has been clearly established in the rho-pi decay channel with a mass of 1660{+-}10(stat) MeV/c{sup 2} and a width of 269{+-}21(stat) MeV/c{sup 2}. The improved detector performance in 2008 allows us to study this channel with significantly higher statistics. First results of the ongoing analysis of the 2008 data taking period, using a 190 GeV/c pion beam on a liquid hydrogen target are presented in this paper.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Study of the all orders multiplicative renormalizability of a local confining quark action in the Landau gauge

The inverse of the Faddeev–Popov operator plays a pivotal role within the Gribov–Zwanziger approach to the quantization of Euclidean Yang–Mills theories in Landau gauge. Following a recent proposal (Capri et al., 2014), we show that the inverse of the Faddeev–Popov operator can be consistently coupled to quark fields. Such a coupling gives rise to a local action while reproducing the behaviour of the quark propagator observed in lattice numerical simulations in the non-perturbative infrared region. By using the algebraic renormalization framework, we prove that the aforementioned local action is multiplicatively renormalizable to all orders.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

The Casimir effect for fields with arbitrary spin

The Casimir force arises when a quantum field is confined between objects that apply boundary conditions to it. In a recent paper we used the two-spinor calculus to derive boundary conditions applicable to fields with arbitrary spin in the presence of perfectly reflecting surfaces. Here we use these general boundary conditions to investigate the Casimir force between two parallel perfectly reflecting plates for fields up to spin-2. We use the two-spinor calculus formalism to present a unified calculation of well-known results for spin-1/2 (Dirac) and spin-1 (Maxwell) fields. We then use our unified framework to derive new results for the spin-3/2 and spin-2 fields, which turn out to be the same as those for spin-1/2 and spin-1. This is part of a broader conclusion that there are only two different Casimir forces for perfectly reflecting plates—one associated with fermions and the other with bosons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Particle mesh Ewald’s method and noninteracting dyon gas

We study the free energy of a quark–antiquark pair near the deconfinement temperature by particle mesh Ewald’s method for noninteracting dyon ensemble. We show that the free energy of the quark–antiquark pair increases linearly by increasing the distance between them. The string tension decreases by increasing the temperature, as expected. - Highlights: • A noninteracting dyon ensemble is studied by particle mesh Ewald’s method. • Free energy of quark-antiquark pair increases linearly by increasing the distance. • Particle mesh Ewald’s method is less time consuming compared with Ewald’s method.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurements of the EMC effect in few-body nuclei at large x

Recent data on the EMC effect from Jefferson Lab experiment E03103 suggest that the nuclear dependence of the high x quark distribution may depend on the local nuclear environment, rather than being a purely bulk effect. We briefly discuss the analysis and results of the E03103 experiment focusing on the light nuclei and high x region. In addition, we also discuss a future experiment at the upgraded 12 GeV Jefferson Lab facility which will further investigate the role of the local nuclear environment and the influence of detailed nuclear structure on the modification of quark distributions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Nucleon Structure from Lattice QCD

Hadron structure calculations in lattice QCD have seen substantial progress during recent years. We illustrate the achievements that have been made by discussing latest lattice results for a limited number of important observables related to nucleon form factors and generalized parton distributions. A particular focus is placed on the decomposition of the nucleon spin 1/2 in terms of quark spin and orbital angular momentum contributions. Results and limitations of the necessary chiral extrapolations based on ChPT will be briefly discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Results on Charmonium(-like) and Bottomonium(-like) States from Belle and BaBar

Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to J/{psi}{gamma} and {psi}'{gamma} its decay into J/{psi}3{pi} and the search for production in radiative Upsilon decays. Another focus is L = 2 mesons, in particlar a possible D-wave assignment to the X(3872) and the confirmation of an Upsilon D-wave state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗